Where is the thumbnails stored? Is it cached?

For paid users, we will pick the main image per post in your website, resize, optimize and store them in one of our image servers. Images on our image servers will be distributed in CDN network that will improve the serving speed for our autocomplete and result page.

For non-paid WordPress websites, we will create thumbnails in their server and images will be directly served from their own server instead.

For non-paid regular websites, we will not create any thumbnail but resize their original image photo on the fly during serving. If the original image size is large, users may notice that.